just a few hours, president obama and mitt romney will face off for the first time on the presidential debate stage. >> hallie jackson has a preview. >> after weeks of debate prep and days of spin, the big night is here. it could make a difference. >> secure our borders -- >> we are going through the worst financial crisis since the great depression. >> president obama is fighting to stay in office. >> they are practicing being pointed but respectful. >> mitt romney looking to br eae new life into his campaign. >> it will be a big stage. more than 50 million people tune in for the first obama-mccain face-off. keeping a close eye on the candidates, fact checkers. >> somebody said we should do in a debate is be on stage and if a candidate lies, i should come on stage and slap them in the face. >> it takes will longer. a fallstaff will work throughout the night to see who is telling the truth. many folks will not listen to 90 minutes of this debate but they will listen to 3 or four sound bites that are the best. >> a new poll shows about 15% of likely voters could have their minds changed